His doctor suggested a glass of wine with dinner, as that can be an appetite stimulant.

If your father in law will drink Ensure or another such supplement, that is good. Some are higher in calories than others. Since you just drink it down, he might be willing to do that as a breakfast. Or, perhaps he'd be willing to drink it as a dinner beverage.

With Mr. N, we had to try several flavors and a couple of brands until he found one that he liked.

How about hardboiled eggs? Would he eat one for breakfast or as a snack in the evening?

Would he be willing to drink milk as a dinner or breakfast beverage?

Breakfast again--make some muffins and freeze them. Bran or carrot, for instance.

Speaking of carrot, Mr. Nutrax has a sweet tooth, so I made carrot cake cupcakes and froze them (no icing).

OP: There was a charming article in the Washington Post recently about how a son got his (I believe) grandfather to gain weight. By using food memories.

I can't remember the exact stories but this is sort of what it said (bascially, I'm making up the examples). The grandfather and grandson would go out to eat at restaurants that served him food that triggered memories in his life, such as, going out for Chinese food and the grandfather would talk about eating specific Chinese foods with his wife when they first got married. Or eating at a deli would remind the grandfather about growing up eating at Jewish delis in NYC. Or whatever. The story went on to say that the grandfather would eat a lot more as he was retelling these stories and remembering the food. The gf ended up gaining back a lot of the weight he had lost.

So perhaps, serving up foods that remind your loved one of good times or other places would help.

Thanks again everyone for the suggestions! I really appreciate it! I can't answer all the questions as to his food preferences because I don't know all of them. But I will be passing lot of these suggestions on to him.

I have encouraged him to drink more milk and suggested whole milk. FIL loves milk, but is hesitant to try whole. He likes his 2%.

Trail mix is generally pretty high in calories and can be eaten anywhere. Also adding granola to breakfast. There's some pretty yummy nuts out there-we found some smoked almonds awhile back that are addictive.

Why doesn't he eat much during the day? Breakfast and lunch would be good places to add in some calories. And if he was eating regularly throughout the day, he might not be so exhausted when he gets home.

Breakfast could be a muffin. You can get a 6 pack of high-fat muffins at just about any supermarket bakery. Instant breakfast on the go. There's even pre-cooked bacon available now.

Breakfast doesn't have to be breakfast food. He could have a sandwich or a salad or a bowl of soup.

Lunch could be a simple sandwich, a sub he picks up from a shop, or even a Lunchable. They sell packs of tuna with crackers for an grown-up Lunchable. Or those instant noodles in a cup, if he has access to hot water. There are tons of things that are pre-packed in single servings. Mostly they are marketed towards kids' school lunches, but I see a lot of adults at work eating them--single serving puddings or Jello, applesauce, canned fruit.

I think if he can make the behavior change to eating more during the day, it would be a big help. Even just a can of Ensure for breakfast and lunch, or Carnation instant breakfast.

As for freezer meals, I find tomato-based dishes freeze well. Chili, spaghetti sauce (with or without meatballs), casseroles with tomatoes and rice rather than cream and pasta. True, he'd have to cook the pasta for spaghetti, but it's about the same amount of work and only a little bit longer than nuking a frozen dinner. Do a pot roast with veggies in a slow cooker, or roast a chicken with some veggies and then divide up into single servings of meat/veggies and freeze.

I'd work on getting enough calories into him to start. Once he's accustomed to eating enough food, then work on the nutritional aspects of what he's eating.

Is the lack of eating enough a new thing, caused by some event in his life, or has it been going on for some time?

Would he eat something like custard for breakfast? You can squeeze a whole lot of calories into it by using half and half and egg yolks.

If he's one of the "just coffee for breakfast" sorts, would he eat something like kringla with it? It's a not very sweet soft cookie sort of affair -- the version I make is basically sour cream, egg yolks, flour and sugar. The lady who gave me the recipe always buttered her kringla before eating, too. <g>

My perpetually underweight brother and I actually gained a lot of weight as preteens off Slim-Fast shakes - my parents were trying to diet and they made the mistake of allowing my brother and I to drink the shakes they bought.

What made me gain weight as an adult was suddenly eating more starches as both the meals I was raised with and my natural inclinations lead me to eat very few starchy foods. As a kid I'd refuse buns on hamburgers. I dated a guy with horrible eating habits, and he always insisted on pasta or bread with every meal - not the worst eating habit, but pasta tended to encourage a drenching in calorie-rich sauces. I gained 55 pounds over the course of three and a half years - I went from underweight to a bit overweight in a fairly short time.

You could also buy him a few bags of shredded cheese - it's easy enough to add a handful of that on top of everything and add a few hundred calories in one step!

I don't know how old your father is, or if he smokes, but one issue that can cause older people or smokers to lose weight is a decrease in their sense of smell and taste. You might want to experiment with increasing the aromatic spices in dishes you prepare for him.

Is the lack of eating enough a new thing, caused by some event in his life, or has it been going on for some time?

It's kind of the result of progressivley eating less and less over the last couple of years. He does smoke (someone asked that), and is naturally thin anyway. He's also had some dental work and lost a tooth during the last year. He has a fake tooth (sorry, I don't know what it's called), but some foods he used to enjoy stick under the tooth next to his gums, or are hard to chew. So he avoids them now.

He generally doesn't eat breakfast because it's just so early when he gets up (he get's to work by 3:30 a.m.). But DH and I have told him that he will need to start eating more during the day.

Someone here suggested muffins, and I just made a big batch for him this weekend and wrapped them individually. Hopefully they will freeze well and he can just pop one in the microwave in the morning.